1. Field of the Invention
The present invention relates to a method of fabricating a light emitting diode chip, and more particularly, to a method of fabricating a light emitting diode chip which is improved in light emitting efficiency through an inclined sidewall of a semiconductor layer formed on a substrate.
2. Discussion of the Background
A light emitting diode (LED), which is a light converting device which has a junction structure of P and N type semiconductors, emits light through recombination of electrons and holes which are moved through the joined region of the P and N type semiconductors when forward voltage is applied. Since the color of the emitted light is determined by an energy gap, the LED of desired color can be fabricated according to a selection of a semiconductor material.
The LED capable of emitting various colors is widely applied to display elements and backlights for a variety of electronic appliances, dash boards, display boards and the like.
Also, the LED has less electric power consumption and longer lifespan as compared with an illuminator, such as a conventional light bulb or fluorescent lamp, so that the applications of the LED are expanded to general illumination while substituting for conventional illuminators. However, light emitting efficiency of the LED is very important in order for the LED to be used for general illumination, and a variety of technologies therefor have been under development.
Generally, the LED is fabricated in such a manner that semiconductor layers are successively formed on a substrate and light emitting regions are formed by etching the semiconductor layers. Then, individual LED chips are fabricated from the fabricated LED through a process of separating the substrate using a diamond tip. Then, the fabricated LED chip is used for manufacturing a white light emitting device for emitting white light through a variety of technologies.
For example, a phosphor is combined to adjust a white balance when a blue LED is used for fabricating a white light emitting device. Hitherto, in order to increase the white light emitting efficiency, most of the study has been devoted to increase of light power of an LED chip, research of EPI, a chip pattern and the like, and improvement of phosphor efficiency.
However, there is a problem in that the white light emitting efficiency has not been improved even though a LED chip with the identical phosphor and increased light power is used.
This is closely related to a characteristic of a directional angle of light emitted from the white LED. Generally, in the LED device such as a white LED, its light is bright at the center portion and becomes weaker as it goes to a side, as viewed from its front. Accordingly, the amount of the phosphor is increased at the center portion in order to adjust a white color ratio when fabricating the white light emitting device. However, a light block phenomenon as much as the increased amount of the phosphor occurs, which causes the white light efficiency of the white LED to be decreased as a result.